1. Field of the Invention
The present invention relates to a method for detecting trouble in a fluid pressure system which includes a fluid pressure source having a fluid pump, a pressure tank connected to the pump, a pressure detector for detecting a fluid pressure in the pressure tank, and a control means for controlling the operation of the fluid pump on the basis of an output signal from the pressure detector, and which is operated by an output pressure from the fluid pressure source, and to methods for detecting trouble in a fluid pressure brake system which comprises a fluid pressure source including a fluid pump, a pressure tank connected to the pump, a pressure detector for detecting a fluid pressure in the pressure tank, and a control means for controlling the operation of the fluid pump on the basis of an output signal from the pressure detector, and which controls the output pressure from the fluid pressure source to a fluid pressure corresponding to an operation quantity to deliver it.
2. Description of the Prior Art
Such fluid pressure systems and such fluid pressure brake systems for vehicles are already known, for example, from Japanese Patent Application Laid-open No. 274958/92 and the like.
In such a system, if the pressure detector gets out of order, or if a defect in fluid pressure is produced in the middle of a fluid pressure path, a sufficient fluid pressure cannot be insured in the fluid pressure source. Thereupon, a technique for detecting trouble in the pressure detector is disclosed in Japanese Patent Application Laid-open No. 345568/92. This prior art technique is intended to detect a high or low level sticking state of the pressure detector on the basis of an output signal from the pressure detector, but is incapable of detecting a trouble at an intermediate level between high and low levels and is also incapable of detecting a defect in fluid pressure produced in the middle of the fluid pressure path.
On the basis of the fact that, if the system is normal, the fluid pressure is varied in accordance with the operation of the system, the trouble will be detected, if the consumption of fluid pressure is monitored during operation of the system.